This is the part where I get to root through my collection and give you my favorites for a budding PC gamer who wants to get in on Golden Age strategy games (and I'll restrict this to games at least five years old
2004: Rome: Total War, still my all-time favorite game. Crusader Kings is excellent if you spend the ten bucks for the Deus Vult expansion---it's a nice intro to Paradox games and the first leg of the Paradox 900.
2003: Rise of Nations, which takes the Age of Empires formula and polishes it to a perfect shine. SimCity 4 is the best of the modern city-builders (and is available cheap these days). Victoria was excellent, but it's not for everyone.
2002: Morrowind, Medieval: Total War, and a little underrated gem called Sid Meier's SimGolf.
2001: Civ 3 (the FAQ I wrote for this game comes up as the first result if you google my name. Spiffy!), Tropico, Europa Universalis 2, and the sublime Capitalism II. This was also the year Warcraft 3 came out (not my cup of tea, but a lot of folks like it.)
1999: Sid Meier's Alpha Centauri. Held my "best game ever" crown for five solid years. Still ranks #2 on my list. I'd say "SimCity 3000" here but that game yacks under XP, never mind Vista/7.
1998: Railroad Tycoon II (I still play this a decade later.) Starcraft came out in '98---again, not my personal cup of tea, but don't take my word for it.
1996: Warcraft II. Poke around on SourceForge and you can play it using the Stratagus engine, which is a nice improvement for the game.
1995: Civilization II (one of the best in the series), Caesar "Plebs are needed!" II (best in its series.)
1993: SimFarm. You can find a Windows version that actually runs in XP (not sure if "XP Mode" in Win7 supports it.) Makes Harvest Moon look like a child's toy.
1989: SimCity Classic, though to be quite honest, the SNES version was for my money the best version of the original game.